DERMASTROLOGY – Reading the Skin Signs
Who is a veterinary dermatologist?
Many owners, even those who work in human medicine, are surprised to hear that there are veterinarians who specialize in only dermatology. Dermatology is a branch of medicine that manages diseases affecting the skin, hair, and nails. Other human specialists may manage allergies, infections, and ear disease, but these are often treated by veterinary dermatologists as well.
Veterinary dermatologists go through undergraduate studies, veterinary school (4 years), a rotating internship (1 year), sometimes a dermatology internship (1 year), and a residency (3 years). After the residency, there is a 2-day board certification exam in order to become a Diplomate of the American College of Veterinary Dermatology (DACVD).
What types of skin diseases are common in dogs and cats?
Many patients are itchy, but not all. Some dermatology dog and cat patients can be spotted in the lobby, but not all. One of the more common problems that we deal with is a secondary bacterial or yeast skin and/or infection, due to a primary dermatologic disease. These infections can look like pimples, red bumps, and circular crusts with hair loss, dandruff, and scratch marks.
One of the frequent underlying primary diseases is allergies: flea, food, and/or environmental. Flea allergy is the most common. Food allergy will be covered in a future blog post. Environmental allergy can develop to things inside or outside the home. Some patients have a combination of these allergies.
Immune-mediated diseases are due to the body attacking its own skin. Sometimes, the trigger for this inappropriate response can be an infectious organism, drug, vaccine, or systemic disease, but often times, the initiating stimulus is unknown.
There are also some skin cancers that are either limited to skin or present with skin signs first. After diagnosis, we often collaborate with other services in the hospital, such as surgery, oncology, and/or neurology, to develop a plan for management of the disease.
What diagnostic tests does a veterinary dermatologist perform?
One of the frustrations of dermatology is that many of the skin lesions appear very similar, despite very different underlying causes. One of the most helpful, immediate, non-invasive tests is cytology. This is simply a fancy word for sampling the skin and then examining the sample under a microscope. Sampling techniques can include plucking hair, rubbing a slide against the skin, taping the skin, gently scraping the skin, and swabbing the ears.
What treatments are often prescribed by a veterinary dermatologist?
Antimicrobials (like antibiotics or antifungals) are often prescribed for infections. Topical solutions are also used very frequently and, in some situations, are preferred over oral systemic medications. There are many different types of anti-itch medications, some with more side effects, limitations, and monitoring than others. For immune-mediated diseases and cancers, other types of medications that affect the immune system are prescribed.
When should my pet see a veterinary dermatologist?
The dermatology service at Friendship Hospital for Animals is available for appointments Monday through Friday, whether for acute severe diseases that require immediate workup, for more chronic diseases that require long-term management and follow-up, or for anything in-between. Your primary veterinarian can also help identify the problem and refer you to us. We look forward to helping your pets!
KIBBLES ‘N ITCH
What is an adverse food reaction (AFR)?
An adverse food reaction is also known as food allergy, hypersensitivity, or intolerance. It is an overreaction by the body’s immune system to a certain ingredient (sometimes multiple) in a diet, typically protein. While food allergy is less common than flea allergy or environmental allergy, it is still important to rule out or diagnose because a) patients can have more than one allergy (even if food allergy is a smaller contributing factor) and b) environmental allergy can only be diagnosed by excluding other diseases (including food allergy).
Why do AFRs develop?
AFRs are thought to develop because of small food proteins leaking out of diseased intestines (ex. affected by a virus, parasites, autoimmune disease, cancer). These proteins that are outside of their normal environment are identified by the immune system as a “foreign invader,” and the body starts to react to these proteins as something negative. The gut and the skin share many of the same immune system cells which is why food allergies in pets show up as skin disease. Some of the more common allergens in dogs and cats include: beef, chicken, soy, dairy, corn, eggs, and fish.
What are the symptoms of AFR?
Animals with food allergy are classically itchy. This can be focused on the mouth, paws, ears, or “rears.” Other pets can present with secondary infections, concurrent with itch or separate. While it is important to treat the infections, it is still more important to treat the underlying allergy to limit these cycles of infection.
These symptoms differ from the classic idea of what food allergy is in humans (ex. peanuts). Anaphylactic reactions are not typical for our patients.
What types of animals develop an AFR?
Any animal could theoretically have an AFR. However, there are some breeds that are more likely to be food allergic, such as cocker spaniels, Labrador retrievers, German shepherds, boxers, and Lhasa apsos. The classic age of onset for AFR is relatively young (<6-months-old) or relatively older (>6-years-old). For these patients, we are more likely to pursue an AFR workup.
How do we diagnose AFR?
The only way to diagnose an AFR is through an 8-12 week strict diet trial, followed by a 2-week challenge. While blood and skin food allergy tests do exist, they are not reliable and often result in false positives and negatives. In the future, we hope there will be faster and more convenient ways to diagnose an AFR.
Why is raw food controversial?
We do not recommend feeding raw food to pets as there is little scientific evidence to support its benefits. The major concerns include:
- Infectious disease risks to both the animal and to humans: raw meats can contain many different types of pathogenic organisms (like E. coli or Salmonella). Indirectly interacting (being licked by the pet, cleaning up after the pet) with a pet that eats raw meat still places the human at risk.
- An unbalanced diet: A raw food diet, especially if not supplemented with other nutrients, may not fulfill all the components that a dog or cat needs.
- Foreign bodies: Some ground-up raw foods may contain some bones which can be dangerous and can block the esophagus or intestines. They may also pose a choking hazard.
For detailed information regarding raw food diets please see:
http://vet.tufts.edu/wp-content/uploads/raw_meat_diets_memo.pdf
Why is grain-free food controversial?
Contrary to popular belief, grain-free diets do not offer health benefits over a diet that contains grains, and each diet should be assessed based on its overall nutrient profile rather than individual ingredients. Dogs and cats can digest and utilize grains as well as other sources of carbohydrates. In general, animal proteins are more common causes of food allergies than grains (or other carbohydrate sources) in both dogs and cats.
For detailed information regarding grain-free diets please see:
http://vet.tufts.edu/wp-content/uploads/DecipheringFactFromFictionGrainFree.pdf
What diets do we use for the food trial?
We recommend a prescription food of either novel protein (something that your pet has not eaten previously, ex. kangaroo) or hydrolyzed protein (the protein is broken down into a smaller size, and the body should not react to it). If your pet is determined to be food allergic, then long-term options are discussed.
